WO2008022495A1

WO2008022495A1 - Method for preparing nanometer metal powder

Info

Publication number: WO2008022495A1
Application number: PCT/CN2006/002913
Authority: WO
Inventors: Huimin Wang
Original assignee: Huimin Wang
Priority date: 2006-08-17
Filing date: 2006-10-30
Publication date: 2008-02-28
Also published as: CN100446900C; CN1911567A

Abstract

A method for preparing nanometer Fe powder is provided. The method solves the problems of congregation and shape irregularity occurred in preparing nanoscale metal powder in the prior art. It includes the steps of applying Fe powder under the processing temperature of -10 ~+10,cutting Fe particles at high frequency of 4000-6000 times/minute, grinding the processed particles at high speed of 4000-6000 rotations/minute, then reducing Fe powder and processing the surface of Fe powder, finally executing classification and selection, resulting in the surface-smooth, spherical and dispersed nanoscale Fe powder.

Description

Metal nano-heap production method

The invention relates to a metal nano powder processing technology, in particular to a metal nano powder zero-bound particle cutting production process.

Background technique

Nanotechnology is an emerging technology that emerged in the 1990s, studying the science of the properties and laws of matter ranging from 0.1 to 100 nanometers. Nanoparticles refer to ultrafine particles having a particle size of the order of nanometers, and the nanoparticles are generally between 1 and 100 nm. When small particle sizes enter the nanometer scale, they have quantum size effects, small size effects, surface effects, and macroscopic quantum tunneling effects, thus exhibiting many unique properties in catalysis, light absorption, medicine, magnetic media, and new materials. There are broad application prospects in other areas. When the size of the nanoparticles is continuously reduced, under certain conditions, the macroscopic physical and chemical properties of the material will be changed, giving them special mechanical, thermal, optical, magnetic and chemical properties. In particular, nano-sized iron powder is widely used in many fields such as machinery, electronics, metallurgy, bioengineering, nuclear industry, chemical, pharmaceutical, textile, military and aerospace. At present, the processing technology of nano-scale iron powder materials in the world mainly includes electrolysis method, water mist method, rapid solidification method, laser method, plasma gas phase reaction method, carbonyl iron thermal decomposition method, chemical liquid phase reduction method and the like. There are many difficulties that are not easy to overcome, such as agglomeration, high temperature, etc.; resulting in poor product shape (such as sheet, irregular), uneven particles, poor fluidity, insufficient strength and so on. Among the metal nano-powder materials, nano-iron powder is the most difficult to process and scale production. Compared with non-ferrous metals, it can be modified only in a protective atmosphere. In particular, powder agglomeration and particle shape are two of iron powder processing. Difficulties, as shown in Figure 6 and Figure 7, these two difficulties directly determine the quality and performance of nano-scale iron powder. In China, processing production of more than 1 micron is blank, and a few of them have different experimental explorations, but the products are basically irregular sheet-like particles, and their uniformity, fluidity, strength, and specific surface area are not up to The requirements of nanomaterials are required in the world market. .

Summary of the invention

The present invention provides a metal nano-powder zero-boundary particle cutting production process in order to solve the problems of powder agglomeration and irregular particle shape which occur in the preparation of nano-sized metal powder materials existing in the prior art.

The invention is realized by the following technical solution, a metal nano powder zero-boundary particle cutting production process, taking iron powder as an example, the steps include: placing the iron powder at -10 ° C ~ +10 ° C (preferably - 6 °C) at the zero boundary processing temperature state, then the high-speed cutting of the iron powder particles, controlled at 4000~6000 times per minute, preferably 6000 times/min), and then the iron powder particles after cutting are 4000~6000 rpm ( Preferred 4000 High-frequency grinding of rpm, physical reduction, surface treatment, and product can be obtained, and finally sorted.

Taking iron powder as an example, the product obtained after processing according to the above steps is analyzed as follows. The iron powder raw material is a reduced iron powder produced directly from iron ore as a raw material for producing zero-boundary particle-cut nano-iron powder.

Table 1

1. Comparison of nano iron powder parameters and data obtained by different methods of nano iron powder produced by the method of the present invention 2

Parameters / Country United States This invention Germany, Japan, Korea, total iron (Fe) 99. 985 99. 98 99. 97 99. 95 Phosphorus (P) 0. 00015 0. 000148 0. 0002 0. 00021 0. 00023 Manganese (Mn) 0 41 0. 23 0. 43 0. 47 0. 39 Carbon (0 0. 00043 0. 00038 0. 00043 0. 00039 0. 000375 Silicon (Si) 0. 21 0. 15 0. 22 0. 24 0. 2 Sulfur (S) 0. 00033 0. 00031 0. 00034 0. 00036 0. 00032 Hydrogen loss 0. 0005 0. 00032 0. 00041 0. 00044 0. 00035 Hydrochloric acid insolubles 0. 00014 0. 00013 0. 00012 0 . 00015 0. 00017 Fluidity (50g/s) 32 46 31 33 31. 6 Bulk density (g/cm ³ ) 0. 51 0. 50 0. 53 0. 512 0. 531 Tap density (g/cm) ³ ) 1. 11 1. 12 1. 09 1. 07 1. 08 Specific surface area (m ² /g) 6. Oi l 8. 326 5. 945 5. 993 7. 047 Antioxidation time (h) 32 101 30 27. 6 31

Oxidation rate (%) 92 31 91 95 96. 32 Particle strength (Mohs) 6. 24 8. 11 6. 18 6. 02 7. 01

D50 particle size (nm) 100 100 100 100 100 particle distribution (nra) 42-143 20-114 51-157 45-161 32-152 2. Through the comparison of electron micrographs of nano iron powders in various countries, the products obtained by the process of the invention have obvious spherical structure and excellent dispersibility.

3. The analysis of the specific data shows that the liquidity is 14 grams higher than that of the foreign products, which fully demonstrates that the iron powder sphere shape of this product is superior to other products; the bulk density is 0. 012 grams less than the foreign products. It indicates that the particle size is much smaller than that of the comparative product, and the tap density and specific surface area indicate that the average particle diameter of the product is smaller than that of the comparative product; the oxidation time is on average 69 hours higher than the comparison product, and the oxidation rate is lower. The particle strength indicates that the quality of the product produced by the present invention is higher than that of the comparative product; the particle distribution indicates that the product obtained by the present invention is relatively concentrated in a certain product segment (D50). The nano-sized iron powder produced by the process of the present invention is 1/8 of the price compared with the HGNS nano-iron powder of NOG Corporation of the United States.

The invention adopts the physical method for cutting iron powder in the state of zero boundary to produce nano-scale iron powder, and breaks through the two major problems of processing micro- and nano-scale fine iron powder in the world, and solves the iron powder in the same way. Key issues such as high temperature, agglomeration, uniformity and shape during processing and production have enabled new breakthroughs in strength and fluidity. Under the premise of solving the problem of agglomeration in processing, make full use of iron powder in the zero boundary state without temperature, no agglomeration, and use high frequency cutting to high frequency, uniform cutting of iron powder particles, so that it reaches the nanometer level, and then The ball is shaped by high frequency grinding itself and the grinding medium. The high-speed rotating airflow is used to scatter the powder in the container, and the difference in weight is used to achieve the purpose of powder classification. The invention fills a blank of metal nano materials in China and breaks the long-term technological monopoly of Europe and the United States. Application examples: Diamond tools and cemented carbide products are multiphase composites produced by powder metallurgy using iron as the binder phase. The iron powder prepared by the process of the invention has the advantages of spherical shape, high purity, good fluidity, high density, easy sintering and high hardness, and large holding power. The iron powder produced by the process of the invention is far less expensive than the cobalt powder, and the performance of the cobalt-based binder can be achieved by the relevant physical quantity control. Compared with Co, Ni and Cu, this product has good wettability, formability, sinterability and large adhesion to diamond. It has suitable mechanical properties such as flexural strength and hardness. The materials W, Wc, TiC;, Cr ₃ C ₂ have good wettability; the expansion coefficient of iron is lower than that of Co, Ni and Cu, and the volume effect is small during heating and cooling, which reduces the tendency of crack occurrence; It has good compatibility with B and Si, and can eliminate compounds such as Fe ₃ C, Fe ₃ Si ₃ , Fe ₃ Si, Fe ₂ Si, FeSi, Fe ₂ B, Fe ₃ (CB), which effectively reduces diamond and viscosity. The internal interfacial tension between the joints improves the adhesion to diamond; iron can reduce the internal interfacial tension of diamond and 6-6-3 bronze, produce chemical bonding, improve the wetting of diamond by 6-6-3 bronze, reduce The amount of copper powder used.

The nano-scale fine iron powder produced by the technology of the invention has particularly obvious monomer particles, and the surface is smooth to form a spherical body, and the particles are hooked, the fluidity is excellent, and the strength is extremely high. It has great advantages in specific applications, such as high-speed drill bits made of fine iron powder from Germany and Russia. The clock is 1400 rpm, the bit temperature is 1150 ° C, and the drill made by the fine iron powder produced by this process has a bit temperature of 850 rpm at a speed of 4000 rpm.

DRAWINGS

1 is an electron micrograph of nano iron powder prepared by the present invention

Figure 2 is a photo of a 1 million-fold electron microscopic irregular sheet polygon of the US "HGNS" 80 nanometer iron powder. Figure 3 is a Japanese 150 nanometer iron powder.

Figure 4 is a 100-nanometer 100-million electron microscope dendrimer photo of Germany

Figure 5 is a photo of a 1 million-fold electron microscope irregular sphere of South Korea 150 nanometer iron powder

Figure 6 shows the agglomeration of nano-iron powder during production and processing.

Figure 7 shows the serious agglomeration of nano-iron powder during production and processing.

Figure 8 is a photo of a 1 micron iron powder megascope produced by the technique of the present invention

Figure 9 is an electron micrograph of (50000 mesh) 50 nm iron powder produced by the present invention.

Figure 10 is a 6 micron electron microscope photograph produced by the present invention.

detailed description

Embodiment 1, a metal nano-powder zero-boundary particle cutting production process, taking iron powder as an example, the steps include: placing the iron powder at a zero-temperature processing temperature of 5 ° C, and then performing high-speed on the iron powder particles Cutting, controlled 4,000 times per minute, and then high-frequency grinding of the iron powder particles after cutting is 4000 rpm, and then high-speed reduction, surface treatment. You can get the product. Final classification and sorting. If the iron powder index is not up to standard, secondary cutting and grinding can be performed.

The specific steps are as follows: 1. Iron ore mining; 2. Mechanical crushing; 3. Water washing; 4. Magnetic separation; 5. Drying; 6. Grinding 100 mesh; 7. High temperature purification; 8. Primary reduction; 9. Cyclone classification; 10 zero boundary particle cutting; 11 secondary classification; 12 high frequency grinding; 13 purification; 14 coating; 15 high speed reduction; 16 surface treatment; 17 parabolic classification; 18 negative pressure classification; 19 fluid volume; 20 vacuum oxygen; 21 packaging; 22 storage. Among them, 1-8 is a raw material obtaining process; 9-22 is a whole process for realizing the present invention. The main equipment used in the process is a high frequency cutting machine, a purification furnace, a coating furnace, a nitrogen generator, a cyclone classifier, a polishing machine, a powder surface treatment machine, and the like.

The raw material uses the primary reduced iron powder as the raw material for cutting the nano iron powder by the zero boundary particle. First, the grading is performed once by the cyclone classifier, and the required iron powder is input into the 髙 frequency cutting machine, and the cutting is performed at a frequency of 6000 times per minute. , and then input into the zero-edge grinding machine, using the iron powder in the zero boundary state and the same point cutting tool to grind the mixture to perform nano-scale cutting, and simultaneously grinding to make the sphere shape, and then perform secondary reduction (reduction) The process is well known to those skilled in the art), so that various physical and chemical indicators meet the requirements of nano iron powder, and at the same time, the iron-containing substance is proposed to increase the purity of the iron powder, and then the iron powder particles. Oxidation-proof coating is carried out to achieve an oxidation prevention time of more than 60 hours, and the oxidation rate is less than 5%, thereby achieving an international level of oxidation prevention index, forming a loose block after the oxidation prevention coating, and then performing the same. High-speed pulverization in a sealed state, the particle diameter is up to the micron level, and then input into the B-level zero-boundary cutting and grinding process, so that the iron powder completely reaches the international level particle size, and then loaded into the secondary cyclone classifier unit, By grading different types and different particle diameters, it is possible to obtain more than 30 products of different particle sizes at the same time. The key to the process lies in the zero-frequency high-frequency cutting and grinding, which can reach the nano-scale iron powder and has an excellent shape, followed by hydrogen-oxygen coating. After the coating process, the anti-oxidation time of the iron powder can be increased. The temperature-controlled cooling device in the process uses the forced circulation of water to cool all the steps in the process, so that the energy consumption can be reduced, especially the cooling of the oxygen-proof coating is extremely important. If the cooling temperature control is not accurate, The anti-oxidation time of the nano-iron powder will be seriously affected in the subsequent process.

Example 2: The procedure and apparatus were the same as in Example 1. The zero boundary processing temperature was controlled at -6 °C, the cutting frequency was controlled at 6000 times/min, and the high frequency grinding was performed at 4000 rpm.

Example 3: The procedure and apparatus were the same as in Example 1. The zero boundary processing temperature was controlled at -10 ° C, the cutting frequency was controlled at 5000 times / minute, and the high frequency was milled at 5000 rpm.

Example 4: The procedure and apparatus were the same as in Example 1. The zero boundary processing temperature was controlled at 10 ° C, the cutting frequency was controlled at 4000 times per minute, and the high frequency was milled at 6000 rpm.

Claims

Rights request

A metal nano-powder zero-boundary particle cutting production process, characterized in that: the step comprises: placing the iron powder at a zero-temperature processing temperature of 10 ° C to + 10 ° C, and then performing the iron powder particles High-speed cutting, controlled at 4000~6000 times per minute, and then high-frequency grinding of the iron powder particles after cutting is performed at 4000~6000 rpm, and then physical reduction, surface treatment, to obtain the product, and finally sorting.

2. The metal nano-powder zero-boundary particle cutting production process according to claim 1, characterized in that: the zero boundary processing temperature is -6 ° C to 0 ° C, high-speed cutting, controlled at 6000 times per minute, high frequency The grinding is controlled at 4000 rpm.